The present invention relates to an optical modulator using a compound semiconductor single crystal which generates an electro-optic effect, and an electric field sensor using the optical modulator.
Some of compound semiconductor single crystals; for example, zinc telluride (ZnTe) and gallium arsenide (GaAs); exhibit a so-called electro-optical (EO) effect in which the refractive index changes by the action of electric field. Such a compound semiconductor single crystal (hereinafter referred to as the “electro-optic crystal”) has been used for an optical modulator and other various optical devices.
Conventionally, most of these optical devices were compliant with electromagnetic waves of a high frequency exceeding 1 THz, but in recent years, research for those which are compliant with electromagnetic waves of a low frequency of 100 kHz or less is being conducted (refer to Non-Patent Document 1).